In the microprocessing methods such as photolithography and the like, a resist is used comprising photosensitive resin or the like in order to form a minute pattern. (Said resist is often called "photoresist" since it has a photosensitivity, but it will be hereinafter referred to as "resist".)
For instance, in the case of producing a semiconductor element, a resist is applied onto a base member such as wafer, and after being subjected to light exposure, a soluble portion of the resist is removed in the development step or the successive removing step.
As the resist removing methods in the prior art, there are a spraying method wherein a resist removing liquid (which is usually called "developing solution" or "removing solution" in the field of photolithography, but in the following, it will be collectively referred to as "removing liquid") is sprayed to a resist on the base member to thereby remove the resist from the base member, and a dipping method wherein the base member having a resist disposed thereon is dipped into a removing liquid to thereby remove the resist on the base member. When required, a treatment for promoting the removal of the resist such as ultrasonic vibration treatment, heating treatment, stirring treatment, pressure circulating treatment, or the like is performed for the removing liquid. After the removal of the resist having been accomplished in this way, the base member is usually washed with the use of a rinsing liquid, followed by subjecting the washed base member to drying.
As for these conventional resist removing methods, there are such problems as will be described below.
That is, usually, finer the pattern formed, the greater the period of time for removing the resist is prolonged. However, when a removing liquid having a high resist solubility is used in order to shorten this period of time, other portion of the resist than the portion thereof to be removed is often swelled to cause a bridge, meander, mutual leaning or trailing between the adjacent resist patterns. In the worst case, said other portion of the resist than the portion thereof to be removed is dissolved, wherein the resulting pattern becomes narrowed in width. Thus, it is difficult to obtain a highly precise resist pattern of a desired size and shape in any case.
On the other hand, in the case where removal of the resist is carried out over a relatively long period of time using a removing liquid which is not so high in solubility, without concern about shortening of the removing period of time, it is possible to form a minute pattern with a satisfactory precision. However in reverse, a considerably large amount of the removing liquid is required in this case. In addition, problems are occasionally caused relative to defective removal that residues of the resist occur particularly at the fine portions, and insufficient removal that the resist portions, which were once removed, are returned to adhere, resulting in negative influences to the successive steps. These problems are hardly resolved in the prior art even by employing the foregoing treatments for promoting the removal of the resist.
Now, as one of the principal and effective methods for producing an ink jet recording head, there is a method in which removal of the resist is performed, which is described in U.S. Pat. Nos. 4,657,631 or 4,775,445 and which is schematically shown in FIG. 4(A) through FIG. 4(F). This method will be later detailed. In this method, on a base member 40 shown in FIG. 4(A) having an energy generating body 41 capable of generating an energy to be utilized for discharging ink disposed thereon is disposed a layer 42 comprising, for example, a positive type photosensitive resin as shown in FIG. 4(B). Then, the photosensitive resin layer 42 is subjected to patterning exposure to form a latent image 43a shown in FIG. 4(C), which is corresponding to ink pathway, on the photosensitive resin layer 42. Thereafter, the photosensitive resin layer 42 is subjected to development, to thereby pattern the photosensitive resin layer 42 as shown in FIG. 4(D). Successively, a material 44 capable of forming a wall for ink pathway is applied to cover the patterned photosensitive resin layer 43 as shown in FIG. 4(E). Then, after the patterned photosensitive resin layer 43 being subjected to exposure, the photosensitive resin layer is removed to form ink pathways 46 as shown in FIG. 4(F). Simultaneously with this step or after this step, a throughhole 45 for supplying ink to the ink pathways 46 is formed. Numeral reference 46a denotes a discharging outlet, through which ink is to be discharged, in communication with the ink pathways 46.
According to the method briefly explained above, there can be produced an ink jet recording head of a relatively high reliability. An ink jet recording device provided with such ink jet recording head is commercially available.
Even for such ink jet recording device, there is a social demand for further improving not only the recording speed but also the quality of an image recorded. As one of ideal ink jet recording heads capable of satisfying such social demand, there can be mentioned an ink jet recording head which is basically provided with numerous ink discharging outlets as many as possible being arranged at a high density.
However, in order to realize such an ink jet recording head provided with numerous discharging outlets at a high density, a matter as will be described in the following is spotlighted as the subject to be solved. That is, there is a tendency that as numerous discharging outlets are arranged at a higher density, the ink discharging characteristics of the discharging outlets as a whole are reduced, possibly due to the step of removing the resist at the time of producing the ink jet recording head.
The above matter is not serious and can be more or less accepted in the case of a head provided with a relatively small number of discharging outlets being arranged at a relatively low density. However, the above matter is a subject which cannot be slighted in the case where numerous discharging outlets are arranged at a high density. Particularly, it is a serious technical subject in the case of a so-called full-line type ink jet recording head which is provided with numerous, for instance, some thousands discharging outlets being arranged at a high density along the entire width of the recording area of a member on which an image is to be recorded, in which numerous electrothermal converting bodies are arranged at a high density on a base member such that they correspond to said numerous discharging outlets. Thus, these various subjects relative to removal of the resist are significant at the time of performing removal of the resist in the production of an ink jet recording head.